King Charles and Queen Camilla are due to arrive in Washington D.C. later today for an historic four-day state visit to mark the 250th anniversary of U-S independence. It comes a day after the shooting at the White House Correspondents' Dinner in the US capital. Buckingham Palace says "a number of discussions have been taking place" with American officials to refine security arrangements for the visit. The visit marks a tense time between the two nations as Donald Trump continues to criticise the Starmer government for not participating in the Iran war.   GUEST: Dr Ed Owens, royal historian and author PRODUCER: Pip Cook